The present invention relates to a transmission circuit, a data-transfer control device and electronic equipment.
In data transmission control using deferential signals, the universal serial bus (USB) standard is known as an interface standard for connecting a personal computer with peripheral devices. The demand for high-speed data transmission is increased in recent years. Products spread among people corresponding to the high speed newly defined in USB 2.0 and in capable of transmitting data with the speed faster than Low Speed, Full Speed defined in USB 1.1. Various methods and means have been devised for transferring data normally in data-transfer control devices corresponding to USB 2.0 standard (see the patent document).
Regarding Low Sped and Full Speed defined in USB 1.1 standard and USB 2.0 standard, a host controller had frequently received data normally even not corresponding to the standards since data transfer rate was low. Hence, there have been few problems in data transfer even in products which were not strictly corresponding to designing requirements regulated as Low Speed and Full Speed defined in USB 1.1 standard and USB 2.0 standard.
High Speed newly defined in USB 2.0 has, however, an extremely high data transmission rate such as 480 Mbps. The high rate sometime causes a receiving circuit in a host controller not to transfer transmitted wave signals, which are corresponding to the standard, if the circuit does not satisfy designing requirements defined by USB 2.0. Namely, some products in the market do not strictly meet designing requirements defined by USB2.0.
When a host controller receiving data does not meet designing requirements defined in the standard for example, the controller frequently does not transfer data normally even if a device controller transmitting data meet these designing requirements and transmits signals of which waveform is corresponding to the standard. Similarly, when a device controller receiving data does not meet designing requirements defined in the standard, the controller frequently does not transfer data normally even if a host controller transmitting data complies with these designing requirements and transmits signals of which waveform is corresponding to the standard.
[Patent Document 1] Unexamined patent publication 2002-344542.
In view of the above issues and overcoming them, the present invention is to provide a transmission circuit, which can transfer data normally with high speed even toward a host controller and a device, which does not meet design requirements defined in the standard, data-transfer control device and electronic equipment.